Dennis McGinley

Gap junctions between sertoli and germ cells of rat seminiferous tubules

Ultrastructural observations of rat seminiferous tubules show clearly the presence of plasma membrane junctions between Sertoli and germ cells in the basal and adluminal compartments. Results obtained from the freeze fracture and thin section techniques were correlated in order to elucidate the nature of these intercellular junctions. We suggest that these intercellular membrane specializations are gap junctions which occur within regions of plasma membrane that also exhibit adherens-like modifications.

Intercellular junction development in maturing rat seminiferous tubules.

Sertoli cells of the seminiferous tubules in immature rats (1–20 days) contain gap and tight junctions in different stages of development as identified in freeze-fracture replicas. Typical gap junctions and gap junction formation were observed between Sertoli cells. Tight junctions were observed to assume a variety of configurations including linear, macular, and extensive occluding complexes. Tight junction formation was also observed. A decrease in the frequency of gap junctions and a corresponding increase in the number of tight junctions was quantitatively shown.

Pigmented penile papules with carcinoma in situ changes

Benign appearing, multifocal, pigmented penile papules were found in three patients, showing the histopathological and electron microscopic changes of carcinoma in situ. Their clinical appearance, relation to other carcinoma in situ lesions, as well as possible pathogenesis are discussed.

Effects of aspirin on tight junction structure of the canine gastric mucosa

The effects of aspirin on the canine gastric mucosal barrier were examined using the freeze-fracture and extracellular tracer techniques. Aspirin treatment (3, 20, or 40 min) resulted in alterations in tight junction complex morphology and permeability. Discontinuities in the apical occluding complex, hyperplastic tight junctions (extensions of the apical tight junction strands radiating over the lateral plasma membrane), and a variability in the number of strands (1-20) comprising the complex were observed. A concurrent increase in lanthanum permeability between nonnecrotic surface mucous epithelial cells was also demonstrated. The results of these experiments may suggest that aspirin-induced impairment of the tight junction complexes between viable gastric mucosal epithelial cells may be a major contributing factor in the etiology of stomach disorders.

Effect of various irrigating fluids on the ultrastructure of articular cartilage

The effect of five different irrigating fluids on the ultrastructure of articular cartilage was studied utilizing the scanning electron microscope. Gross histologic studies have shown no significant difference amongst commonly used irrigating fluids on the surface or matrix composition of articular cartilage. Recent in vivo and in vitro biochemical studies, in addition, have shown no significant deleterious effects of irrigating fluids on articular cartilage composition. This study was prospectively undertaken to assess the effect of irrigating fluids on the ultrastructure of articular cartilage. When comparing five irrigating solutions utilizing the scanning electron microscope, specimens irrigated with 1.5% glycine seemed to show a more consistently smooth appearance. Ultrastructural changes were noted with the other four irrigating solutions tested.

The gastric mucosal barrier: structure of intercellular junctions in the dog

The canine gastric mucosa consists of two regions, the surface mucous cells and gland area cells including parietal, chief, and mucous-containing cells. We have used quantitative freeze-fracture methods in conjunction with thin-section extracellular tracers to document and correlate tight junction morphology with epithelial permeability. The number of strands in the tight junction complexes of the surface cells and gland cells is the same, but differences in strand arrangement exist. The surface cells have an interwoven tight junction configuration which is impermeable to extracellular tracers. The gland cell junctions are regularly arranged and often permeable to extracellular lanthanum. The possibility that the observed difference in permeability between the tight junctions of the surface mucous cells and those of the gland cells is related to their structural configuration is discussed.

Intercellular junctional specializations in human basal cell carcinoma

Intercellular junctions of various types were found on the membrane fracture faces of human nodular basal cell carcinoma (BCC) cells. The junctional types represented include desmosomes, tight junctions, and gap junctions. A semiquantitative comparison of undifferentiated and differentiated nodular BCC showed that gap and tight junctions were observed on all exposed membrane fracture interfaces of the differentiated tumors, while only fifty six per cent of the membrane interfaces of the undifferentiated tumor exhibited similar junctional specializations. These membrane specializations may be a partial reflection of differentiation among the different types of BCC and their contribution to the less invasive character of nodular BCC cannot be ruled out.

The gastric mucosal barrier: tight junction structure in gastritis and ulcer biopsies.

Tight junctions of the human gastric mucosa were examined using quantative freeze-fracture methods. Biopsies examined were from patients with gastric diseases including gastritis, ulcers, and pernicious anemia. No significant differences were seen in strand number or tight junction complex depth among the biopsies analyzed, however, anomalous tight junction structures were observed. Discontinuities in the tight junction complex and hyperplastic tight junctions (extensions of the apical tight junction strands radiating over the lateral plasma membrane) were seen. These alterations were not associated exclusively with either the diagnosis of gastritis or ulcers. However, a higher frequency of tight junction breaks was seen in stomach biopsies diagnosed as gastritis while those diagnosed as ulcers displayed a higher occurrence of hyperplastic tight junctions.

The effects of follicle-stimulating hormone (FSH) on sertoli cell junctions in vitro: A freeze-fracture study

The mechanism(s) for the control of Sertoli cell tight junction development and orientation has not been established. We have studied the effect of FSH (5 U/ml) on tight junction formation using an organ culture technique that allows maintenance of tubular structure and viability of Sertoli cells, without the other influencing factors that are encountered in vivo . Tight junctions developed as the control organ cultures aged and consisted of extensive junctional complexes by 30–40 days in culture. Yet their development did not correspond to that seen in the maturing animal at 30 days, remaining basically unoriented. In the 30- to 40-day FSH-treated cultures the tight junctions were not only aligned parallel to one another, but were also condensed in bands at the basal part of the Sertoli cell and seemed to be oriented parallel to the myoid cell layer. These observations suggest that FSH affects the tight junctions of Sertoli cells by influencing their overall orientation. Additionally, the occurrence and possible significance of a septate-like character of the Sertoli junctions that was occasionally noted is discussed.

Development of sertoli cell junctions in vitro—A freeze-fracture study

SummarySeminiferous tubules of 1-day-old rats were maintained in organ culture for up to 40 days. Five classes of intercellular junctions between Sertoli cells were observed by the freeze-fracture method as the tissue aged: (a) typical gap junctions; (b) focal tight junctions; (c) macular tight junctions; (d) meandering tight junctions; and (e) extensive tight junctions. The relative proportions of these types of Sertoli cell junctions were quantitated as the organ cultures progressed. The junctional structures observed and classified in organ culture were identical to those seen in vivo, but the timing of their appearance and/or disappearance, as well as their relative proportions, was different from that observed in the developing animal. Extensive tight junctions, with numerous parallel strands, were observed in the 40-day cultures; however, their oblique orientation with respect to the myoid layer was in contrast to the parallel orientation observed in vivo.